1. Field of the Invention
The present invention relates to display devices having illuminated figures such as symbols, letters, numbers, ideograms and/or combinations of the same, intended to be used in signs, billboards, labels for signals, message boards or any similar examples and/or applications. It also relates to molds useful for the formation of the same.
2. Description of the Background
One of the current techniques for making such display devices consists of making the figure ("figurative element") as a transparent or translucent sector of a sheet, with the rest of the sheet composed of a contrasting background, and behind which a light source is installed with which it is possible to emit a degree of luminosity that permits the figure thus represented to be distinguished at a distance. Obviously, this figure will only be clearly visible in a proportionally reduced visual radius with lower degrees of luminosity, since the same is limited to the amount of light which passes through the surface encompassed by the mentioned sector of the sheet, and which generally does so as radiation oriented perpendicularly to this surface. Typical examples are shown in U.S. Pat. Nos. 2,299,331 (Marinone); 3,978,599 (Berger); 4,798,170 (Pederson et al); 4,891,896 (Boren) and 5,237,766 (Mikolay).
When there is a need to obtain a strong luminosity and, moreover, be visible in an ample radius, one resorts to the use of neon tubes to form the figure. However, this device involves a very complex realization, not only for the tube itself but also for its assembly and the electrical installation required, which carries a high degree of danger due to the high voltage with which it operates. In addition, neon tubes are very fragile, which noticeably restricts the extent of their application. Furthermore, neon tubes are highly likely to suffer deterioration caused by weather conditions when, as usually occurs, they are installed outdoors. Another disadvantage of neon tubes lies in the fact that when one tries to obtain a figure that includes various colors, the figure can only be realized through a combination of neon tubes, one for each color. To all of the above must be added the high cost of figures made with these neon tubes and the need for their regular maintenance.
Display devices such as signs which contain sheets with figures of any complexity are most readily formed by molding. However, the problems which the production of molds in general present are well known, not only for the difficulties inherent in the reproduction of the shape that one wishes to mold, but also for the high cost of the mold, which becomes particularly appreciable when one endeavors to mold a small or reduced quantity of pieces. When, for example, one endeavors to reproduce a specific piece by means of thermoforming, one is required, as is known, to make a mold appropriate for this technology, male or female depending on the circumstance, which permits a vacuum or pressure to be exerted over the sheet of plastic material heated to the necessary temperature and placed so as to cover the projection or concavity of the mold. In the case of a vacuum process, the mold must provide multiple perforations which permit the vacuum to be exerted through the mold over most of its extended area, while in the case of an air pressure process, a chamber must be formed which encompasses all the area of the mold in which the air is injected which will force the sheet to adapt to the shape of the same. In addition, in this case of a pressure process, one could choose to use a top mold which cooperates with the base mold and forces the sheet, when pressed between both, to adapt itself on both faces to the shape of one or the other. As a result, not only is it necessary to make a mold for each piece or group of like pieces which one wishes to mold, but frequently also the mold, once used, must be discarded, requiring another amount of material for the new mold that one is interested in making.
Wire or rod containing molds have been described in the prior art; see, e.g., U.S. Pat. Nos. 3,596,869 (Humphrey) and 5,330,343 (Berteau). They have, however, not been readily adjustable in both length and width to provide for firm retention of the rods or wires during molding but still facilitate sliding motion when the mold is being formed around the model.